Why Facebook keeps giving technology it invented away for free

At this week's Facebook F8 developer conference alone, the social network released free tools to help mobile developers build better interfaces, and for Android developers to understand how their apps are being used, and for making apps crash less when they run out of memory.

In the past, Facebook has given out technologies it invented like Cassandra, used by Apple, Netflix, and many more tech companies to manage their tremendous and growing amounts of data.

The Facebook team shrugs off any concerns that giving away this technology for free is actually losing anything.

"The technology we have isn't our competitive advantage," Occhino says. "Our advantage is the thing that we built."

He's right: Facebook's value comes from the 1.4 billion people who use the social network. That audience reinforces itself — you have to use Facebook because everybody else uses Facebook — making it hard for competitors to catch up. And that audience is how Facebook makes money, by selling their attention to advertisers.

Meanwhile, by giving non-critical technology to whoever wants it, Facebook makes its own apps and tools work better — and ensures that there's a broader base out there of future employees who know exactly how to work with the company's technology.

At a very basic level, React Native takes the stuff that Facebook uses to build its own user interfaces across the web (including the web versions of Instagram and WhatsApp), and lets anybody else do it.

The major advantage, says Wolff, is that it helps developers think about the interface first, ensuring that whatever you do in the app's plumbing doesn't gum up the works in a way a user would ever see. The upside is that the people who make the apps get to move a lot faster without worrying too much about breaking stuff.

"It's still really hard to build mobile apps and make them great," Wolff says.

Facebook has been using React in various ways for the last three years. But by opening the doors up to its code, two things happen: Other developers look at it and say, yeah, this is cool, but this would be better. As the code that Facebook releases gets out and finds its audience, Facebook can take in their improvements and make it better.

(This, incidentally, is the positive side behind of "open source," where everybody from Microsoft to Netflix to VMware releases stuff to the community.)

The other thing that happens is that those developers who work on the stuff Facebook releases often come to work for Facebook itself, sooner or later. It means they can be productive and get right to work on Facebook's systems on day one, Wolff says.

Just don't expect Facebook to give away anything really valuable — like the technology it uses to figure out which advertisements to place in your news feed.